In short, lighting control systems deliver the correct amount of light, where you want it, when you want it. Lights can automatically turn on, off or dim at set times or under set conditions; facilities managers can make changes to lighting when appropriate or to meet financial incentives; and users can have control over their own lighting levels to provide optimal working conditions. Lighting control helps to reduce costs and conserve energy by turning off (or dimming) lights when they are not required.
Customers of lighting control systems often apply a set of “lighting control strategies” or applications, each of which uses a specific technology and method to control a subset of lighting usage. These strategies include occupancy sensing, daylighting, scheduling, task tuning and more.
Lighting control systems vary widely according to the technologies used to complete these tasks, as well as their degree of difficulty and cost. Historically though, the more system-wide controls and advanced strategies that are used, the greater the complexity, which can make these solutions difficult or even impossible to implement across large-scale environments.
Lighting control systems include some or all of the following:
• on/off and dimming controls
• occupancy sensors to detect whether rooms are occupied
• photosensors to detect the current illumination levels provided by natural and/or artificial light
• scheduling that turns on, off, and dims luminaires at preset times
• a centralized control system interface (such as a wall panel or computer software) to manage all of the above
• a method of communication between the lighting equipment and control system
• a method of measuring, displaying, and responding to lighting energy usage
Scheduling and timers
The simplest lighting control systems turns off (or dim) lights at a specified time when the building is assumed to be empty, and turns lights back on again before people arrive for work the next day. This is a start, but with today’s offices where people are increasingly working longer, more flexible hours, additional controls are needed.
Occupancy sensors are useful not only to address flexible working hours, but also to control lights in areas with irregular usage patterns. When the sensors detect that someone has entered an area, the lights corresponding to the location in which the person is detected can be brightened to provide sufficient illumination. Occupancy sensors can also be used to create “corridors of light” to follow people like security guards and cleaners as they move through a building.
Photosensors and Daylighting
One of the greatest areas of potential savings is to reduce lighting when illumination is already being provided through natural sources. When sunlight comes through windows or skylights, photosensors can detect the level of natural illumination and dim or even turn off lights in the area. And as the
natural light fades, the lights can automatically fade back up to the appropriate level. This helps not only to conserve lighting energy, but also to reduce the amount of heat being emitted by the electric lights, which in turn can help save money on air conditioning costs.
Traditional lighting systems in existing buildings were often designed to meet a single, consistent level of illumination across all areas, regardless of workers’ needs. This results in over-lighting for many users’ specific tasks.
Task tuning allows system administrators and individuals to instead tune down maximum lighting levels in each area of a building via dimmable lights, based on user requirements.
Similarly, lighting control systems can also place greater personal control in the hands of individuals. People often require different levels of lighting depending on factors such as their age and the type of work they are doing. Lighting systems can provide the ability for office workers to adjust personal lighting levels directly from the PCs on their desks.
System-wide and Individual Control
In older lighting designs, one room is controlled by one switch in a closed loop, and a facility manager could only access the lighting by physically accessing each room. Lighting control systems can change this equation by linking together the control of an entire building or even separately located buildings, and remotely managing and controlling light settings. This vastly improves ongoing management cost and complexity, and provides the capability for facilities managers to reduce energy use in ways that were never before possible.
In addition, each light and device within a lighting control system can be individually addressable. The lighting system uses these addresses to control individual lights, groups of lights, entire floors and entire buildings. Individual lights can belong to multiple groups to provide great levels of flexibility.
Better data often equals better savings, and this is certainly the case in lighting control. With advanced lighting control systems, facility managers can access real-time and historical information about the usage of energy by light, room, zone, building and more. This provides them with a set of tools for better decision-making, as well as the ability to test new strategies, verify results, and make changes over time to get the most energy savings out of their system.
Increasingly, utilities are offering tremendous incentives for buildings to go beyond simple energy efficiency and reduce their demand for energy at peak times. Although these peak times might be rare, reducing demand can make a significant difference – the top 100 hours of electricity use during the year accounts for as much as 20% of total U.S. electricity costs. Lighting control systems can tie into utility demand management and peak-day pricing programs, allowing facility managers to temporarily reduce lighting use in order to gain financial incentives.